This is a multicore cable in which the cores are not arranged in a circular bundle in a round insulating tube, but are routed parallel to each other. It is primarily used for connecting multi-pole signal lines in electronic assemblies and computers.
Multi-core flat ribbon cables have the advantage that a large number of cores can be connected with little effort using the insulation displacement technique with a pin connector, a soldering adapter or another connector (e.g. D-Sub connector) instead of having to strip them individually and then solder them.